Abstract: A reciprocating engine, preferably a high speed internal combustion engine, includes means for reducing vibration.The engine has at least one piston, a connecting rod connected at one end to the piston and at the other end to a crankshaft. A pair of balancing links are pivotally mounted on the crankshaft and guide links constrain the balancing links to follow paths generally normal to the crankshaft axis and in opposition to the piston.The guide links extend in opposite directions and are attached to the balancing links and to a fixed point to balance out the vibrational forces of the engine.